Arabo Babakhani thought his roommate at University of Central Florida was just a quiet loner until James Oliver Seevakumaran aimed a gun at him Monday in what was intended to be the beginning of a yet another school massacre.

"I just thought he kept to himself a lot and, I don't know, I just thought he was a quiet introverted person. The only time he made solid eye contact with me was when he was pointing the gun at me," Babakhani said.

Babakhani slammed the bathroom door and called 911. The quick response of police derailed Seevakumaran's plans. He shot and killed himself, leaving behind an arsenal that included homemade bombs, and writings that showed how meticulously he planned his attack.

Babakhani's recounted his close call with the university's Knightly News newspaper.

"As he was like raising the gun, he didn't get it all the way up, as he was raising the gun I slammed the door on him before he could pop anything off," Babakhani told the university's Knightly News newspaper.

Babakhani told the 911 dispatcher that his roommate had a gun and was pointing it at him, threatening to shoot, according to the university.

Campus police said that officers had already begun responding to a fire alarm at Tower 1 residence hall that Seevakumaran had pulled when they received the 911 call from Babakhani. Officers responded to the apartment within minutes.

Seevakumaran's plan was to flush students out into the hallways, and open fire on them with multiple weapons and homemade bombs.

When the police arrived, they rescued Babakhani from the bathroom and then found Seevakumaran dead from a self-inflicted gunshot wound to the head. In the apartment, they found a handgun, assault weapon, hundreds of rounds of ammunition and a high capacity drum magazine, as well as four homemade improvised explosive devices that were lined with shrapnel.

Cops also found writings that showed Seevakumaran had put extensive thought into his plans to hurt as many students as possible.

"Anybody armed with this type of weapon could have hurt a lot of people there, particularly in a crowded area as people were evacuating," said university police chief Richard Beary. "It could have been a very bad day."

Seevakumaran, 30, was no longer enrolled at the university and was in the process of being evicted from the dorms. He had been a student until the end of the fall semester in 2012, but had not re-enrolled in January 2013. Police said he began collecting the weapons for the planned shooting in early February.